Polyester which exhibits melt anisotropy has good workability in molding despite its high heat resistance, and therefore has found widespread use in various industrial fields.
Above all, a liquid crystal polyester as a copolymer of hydroxybenzoic acid with polyethylene terephthalate appear to be the most promising with an additional economic advantage. However, such a liquid crystal polyester is disadvantageous in that the homopolymer component of the hydroxybenzoic acid tends to cause phase separation and that the thermal deformation temperature is low and the thermal stability during melt retention is poor. Many different attempts have been made to solve these deficiencies, but none have proven to be completely effective to date.